I've been under the assumption that high shutter speeds would compensate for unsteady hands, and that I can get a sharp picture if my shutter was fast enough. But from my experience with action photography, that doesn't seem to be case.

I typically use speeds of 1/300 and faster when shooting action, and sometimes I would move the camera to track the target. However, when I do so, the subject would be invariably be not sharp. Even when I use shutter speeds of >
1/1000 this phenomenon still occurs, to my great disappointment.

I'm shooting with a 50mm F1.4 on a 40D, using one-shot focus. It is tack sharp when I'm holding the camera steady. I'm forced to get into the habbit of stopping my hand motion as soon as I acquire focus, and then complete the shot. Of course the subject would be a little off course by the time the shot is taken.

Is this pretty much expected behavior? How should I best go about action shots when I need follow a moving target? Would one of the other focus drive modes be better for such shots?

I haven't tried the other focus modes since I assume that the lag necessary for the lens acquire focus constantly on a moving target cannot keep up with the action.